Stabilized imaging system

Abstract

A stabilized imaging system in which the lens assembly is fixed, and an electro-optic imager element is moveable to compensate for three-dimensional movements of the surrounding structure. Preferably the optical train also includes a movable prism, which can rotate the field of view in one plane. Rotation of the imager compensates for the image rotation caused by rotation of the prism.

What is claimed is: 
     
       1. A reconnaissance system, for mounting in an air vehicle, comprising: an optical train, positioned to define a fixed focal plane   and comprising at least one reflector rotatable to change the external solid angle imaged onto said focal plane;     sensors connected to sense multiple parameters corresponding to attitude components of said air vehicle;   an electro-optic imager, movable within the focal plane defined by said lens; and   a controller, actuator and linkage which are connected to move said imager within said focal plane in response to outputs of said sensors, to compensate for motions of the air vehicle in at least one rotational axis,   and also to compensate for image orientation changes due to rotation of said rotatable reflector,     wherein said rotatable reflector is mounted to rotate about an axis which is substantially parallel to the roll axis of the air vehicle, and wherein said imager is moved in accordance with pitch axis motions of the air vehicle.   
     
     
       2. A reconnaissance system, for mounting in an air vehicle, comprising: an optical train, positioned to define a fixed focal plane   and comprising at least one reflector rotatable to change the external solid angle imaged onto said focal plane;     sensors connected to sense multiple parameters corresponding to attitude components of said air vehicle;   an electro-optic imager, movable within the focal plane defined by said lens; and   a controller, actuator and linkage which are connected to move said imager within said focal plane in response to outputs of said sensors, to compensate for motions of the air vehicle in at least one rotational axis,   and also to compensate for image orientation changes due to rotation of said rotatable reflector,     wherein said rotatable reflector is mounted to rotate about an axis which is substantially parallel to the roll axis of the air vehicle,   and wherein said controller is connected to cause rotation of said imager, during at least some time periods, at a rate which is equal to the sum of the image rotation rate due to rotation of said reflector   plus   the rate of rotation of said air vehicle about the yaw axis thereof.     
     
     
       3. A reconnaissance system, for mounting in an air vehicle, comprising: an optical train, positioned to define a fixed focal plane   and comprising at least one reflector rotatable to change the external solid angle imaged onto said focal plane;     sensors connected to sense multiple parameters corresponding to attitude components of said air vehicle;   an electro-optic imager, movable within the focal plane defined by said lens; and   a controller, actuator and linkage which are connected to move said imager within said focal plane in response to outputs of said sensors, to compensate for motions of the air vehicle in at least one rotational axis.   also to compensate for image orientation changes due to rotation of said rotatable reflector,     wherein said actuator and linkage are connected to move said imager within said focal plane with two degrees of freedom, including rotation and one direction of translation.   
     
     
       4. A reconnaissance system, for mounting in an air vehicle, comprising: an optical train, positioned to define a fixed focal plane   and comprising at least one reflector rotatable to change the external solid angle imaged onto said focal plane;     sensors connected to sense multiple parameters corresponding to attitude components of said air vehicle;   an electro-optic imager movable within the focal plane defined by said lens; and   a controller, actuator and linkage which are connected to move said imager within said focal plane in response to outputs of said sensors, to compensate for motions of the air vehicle in at least one rotational axis,   and also to compensate for image orientation changes due to rotation of said rotatable reflector,     wherein said controller, actuator and linkage are connected to move said imager within said focal plane to compensate for yaw and crab of the air vehicle.   
     
     
       5. A medium-altitude reconnaissance system, comprising: a lens system, mountable to an air vehicle at a substantially fixed pointing angle;   an imager movable with multiple degrees of freedom, and aligned with said lens assembly in an optical train which images said imager onto an external strip;   a movable pointing element, aligned with said lens system to steer the field of view thereof;   control electronics, connected to control movements of said imager at least partially in compensation for movements of the air vehicle to which said lens assembly is mounted;   and wherein said lens assembly is not movable to compensate for movements of the air vehicle,   wherein said control electronics are connected to control movements of said imager in accordance with parameters including roll, pitch, and yaw rates of said air vehicle.   
     
     
       6. A medium-altitude reconnaissance system, comprising: a lens system, mountable to an air vehicle at a substantially fixed pointing angle;   an imager movable with multiple degrees of freedom, and aligned with said lens assembly in an optical train which images said imager onto an external strip;   a movable pointing element, aligned with said lens system to steer the field of view thereof;   control electronics, connected to control movements of said imager at least partially in compensation for movements of the air vehicle to which said lens assembly is mounted;   and wherein said lens assembly is not movable to compensate for movements of the air vehicle,   wherein movement of said imager within said focal plane is controlled to compensate for motions of the air vehicle about the yaw axis thereof.   
     
     
       7. A medium-altitude reconnaissance system, comprising: a lens system, mountable to an air vehicle at a substantially fixed pointing angle;   an imager movable with multiple degrees of freedom, and aligned with said lens assembly in an optical train which images said imager onto an external strip;   a movable pointing element, aligned with said lens system to steer the field of view thereof;   control electronics, connected to control movements of said imager at least partially in compensation for movements of the air vehicle to which said lens assembly is mounted;   and wherein said lens assembly is not movable to compensate for movements of the air vehicle,   wherein said imager is movable, within the focal plane defined by said optical train, with at least two degrees of freedom.   
     
     
       8. A medium-altitude reconnaissance system, comprising: a lens system, mountable to an air vehicle at a substantially fixed pointing angle;   an imager movable with multiple degrees of freedom, and aligned with said lens assembly in an optical train which images said imager onto an external strip;   a movable pointing element, aligned with said lens system to steer the field of view thereof;   control electronics, connected to control movements of said imager at least partially in compensation for movements of the air vehicle to which said lens assembly is mounted;   an wherein said lens assembly is not movable to compensate for movements of the air vehicle,   wherein said imager is movable, within the focal plane defined by said optical train, with exactly two degrees of freedom.   
     
     
       9. A medium-altitude reconnaissance system, comprising: a lens system, mountable to an air vehicle at a substantially fixed pointing angle;   an imager movable with multiple degrees of freedom, and aligned with said lens assembly in an optical train which images said imager onto an external strip;   a movable pointing element, aligned with said lens system to steer the field of view thereof;   control electronics, connected to control movements of said imager at least partially in compensation for movements of the air vehicle to which said lens assembly is mounted;   and wherein said lens assembly is not movable to compensate for movements of the air vehicle,   wherein said imager is movable, within the focal plane defined by said optical train, in rotation and in one direction of translation   
     
     
       10. A medium-altitude reconnaissance system, comprising: a lens system, mountable to an air vehicle at a substantially fixed pointing angle;   an imager movable with multiple degrees of freedom, and aligned with said lens assembly in an optical train which images said imager onto an external strip;   a movable pointing element, aligned with said lens system to steer the field of view thereof;   control electronics, connected to control movements of said imager at least partially in compensation for movements of the air vehicle to which said lens assembly is mounted;   and wherein said lens assembly is not movable to compensate for movements of the air vehicle,   wherein said controller, actuator and linkage are connected to move said imager within said focal plane to compensate for yaw and crab of the air vehicle.   
     
     
       11. A medium-altitude reconnaissance system, comprising: a lens system, mountable to an air vehicle at a substantially fixed pointing angle;   an imager movable with multiple degrees of freedom, and aligned with said lens assembly in an optical train which images said imager onto an external strip;   a movable pointing element, aligned with said lens system to steer the field of view thereof;   control electronics, connected to control movements of said imager at least partially in compensation for movements of the air vehicle to which said lens assembly is mounted;   and wherein said lens assembly is not movable to compensate for movements of the air vehicle,   wherein said controller, actuator and linkage are also connected to move said imager normal to said focal plane to achieve a desired range focus.   
     
     
       12. A medium-altitude reconnaissance system comprising: a lens system, mountable to an air vehicle at a substantially fixed pointing angle;   an imager movable with multiple degrees of freedom, and aligned with said lens assembly in an optical train which images said imager onto an external strip;   a rotatable optical element which, with said lens system and said imager, forms an optical train which images external objects onto said imager, said rotatable optical element being positioned to steer the field of view of said optical train;   wherein said rotatable optical element is located in very close proximity to a pupil of said lens system,   wherein motion of said imager within said focal plane is controlled to compensate for motions of the air vehicle about the yaw axis thereof.   
     
     
       13. A medium-altitude reconnaissance system, comprising: a lens system, mountable to an air vehicle at a substantially fixed pointing angle;   an imager movable with multiple degrees of freedom, and aligned with said lens assembly in an optical train which images said imager onto an external strip;   a rotatable optical element which, with said lens system and said imager, forms an optical train which images external objects onto said imager, said rotatable optical element being positioned to steer the field of view of said optical train;   wherein said rotatable optical element is located in very close proximity to a pupil of said lens system,   wherein said imager is movable within said focal plane with two degrees of freedom, including rotation and one direction of translation.   
     
     
       14. A method for performing aerial reconnaissance, comprising the steps of: flying an air vehicle along a track which is within view of a desired area to be imaged, wherein said air vehicle includes: a lens system mounted substantially fixedly;   an electro-optic imager mounted in the focal plane of said lens system, wherein said imager is controllably movable in at least one direction of translation substantially within the focal plane of said lens assembly,   a rotatable optical element which, with said lens system and said imager, forms an optical train which images external objects onto said imager, said rotatable optical element being positioned to steer the field of view of said optical train;     imaging the desired area, while maneuvering the air vehicle freely; and   moving said imager during said imaging step, to compensate at least partially for motions of the air vehicle,   wherein said imager is moved during imaging in accordance with parameters including roll, pitch, and yaw rates of the air vehicle.   
     
     
       15. A method for performing aerial reconnaissance, comprising the steps of: flying an air vehicle along a track which is within view of a desired area to be imaged, wherein said air vehicle includes: a lens system mounted substantially fixedly;   an electro-optic imager mounted in the focal plane of said lens system, wherein said imager is controllably movable in at least one direction of translation substantially within the focal plane of said lens assembly,   a rotatable optical element which, with said lens system and said imager, forms an optical train which images external objects onto said imager, said rotatable optical element being positioned to steer the field of view of said optical train;     imaging the desired area, while maneuvering the air vehicle freely; and   moving said imager during said imaging step, to compensate at least partially for motions of the air vehicle,   wherein said rotatable element is mounted to rotate about an axis which is substantially parallel to the roll axis of the air vehicle, and wherein said imager is translated in accordance with pitch axis motions of the air vehicle.   
     
     
       16. A method for performing aerial reconnaissance, comprising the steps of: flying an air vehicle along a track which is within view of a desired area to be imaged, wherein said air vehicle includes: a lens system mounted substantially fixedly;   an electro-optic imager mounted in the focal plane of said lens system, wherein said imager is controllably movable in at least one direction of translation substantially within the focal plane of said lens assembly,   a rotatable optical element which, with said lens system and said imager, forms an optical train which images external objects onto said imager, said rotatable optical element being positioned to steer the field of view of said optical train;     imaging the desired area, while maneuvering the air vehicle freely; and   moving said imager during said imaging step, to compensate at least partially for motions of the air vehicle,   wherein motions of said rotatable element and of said imager within said focal plane provide compensation for motions of the air vehicle about both roll and pitch axes thereof.   
     
     
       17. A method for performing aerial reconnaissance, comprising the steps of: flying an air vehicle along a track which is within view of a desired area to be imaged, wherein said air vehicle includes: a lens system mounted substantially fixedly;   an electro-optic imager mounted in the focal plane of said lens system, wherein said imager is controllably movable in at least one direction of translation substantially within the focal plane of said lens assembly,   a rotatable optical element which, with said lens system and said imager, forms an optical train which images external objects onto said imager, said rotatable optical element being positioned to steer the field of view of said optical train;     imaging the desired area, while maneuvering the air vehicle freely; and   moving said imager during said imaging step, to compensate at least partially for motions of the air vehicle,   wherein motion of said imager within said focal plane is controlled to compensate for motions of the air vehicle about the yaw axis thereof.   
     
     
       18. A method for performing aerial reconnaissance, comprising the steps of: flying an air vehicle along a track which is within view of a desired area to be imaged, wherein said air vehicle includes: a lens system mounted substantially fixedly;   an electro-optic imager mounted in the focal plane of said lens system, wherein said imager is controllably movable in at least one direction of translation substantially within the focal plane of said lens assembly,   a rotatable optical element which, with said lens system and said imager, forms an optical train which images external objects onto said imager, said rotatable optical element being positioned to steer the field of view of said optical train;     imaging the desired area, while maneuvering the air vehicle freely; and   moving said imager during said imaging step, to compensate at least partially for motions of the air vehicle,   wherein said rotatable element is mounted to rotate about an axis which is substantially parallel to the roll axis of the air vehicle,   and wherein said controller is connected to cause rotation of said imager, during at least some time periods, at a rate which is equal to the sum of the image rotation rate due to rotation of said rotatable element   plus   the rate of rotation of said air vehicle about the yaw axis thereof.     
     
     
       19. A method for performing aerial reconnaissance, comprising the steps of: flying air vehicle along a track which is within view of a desired area to be imaged, wherein said air vehicle includes: a lens system mounted substantially fixedly ;   an electro-optic imager mounted in the focal plane of said lens system, wherein said imager is controllably movable in at least one direction of translation substantially within the focal plane of said lens assembly,   a rotatable optical element which, with said lens system and said imager, forms an optical train which images external objects onto said imager said rotatable optical element being positioned to steer the field of view of said optical train;     imaging the desired area, while maneuvering the air vehicle freely; and   moving said imager during said imaging step, to compensate at least partially for motions of the air vehicle,   wherein said imager is movable within said focal plane with two degrees of freedom, including rotation and one direction of translation.   
     
     
       20. A method for performing aerial reconnaissance, comprising the steps of: flying an air vehicle along a track which is within view of a desired area to be imaged, wherein said air vehicle includes: a lens system mounted substantially fixedly;   an electro-optic imager mounted in the focal plane of said lens system, wherein said imager is controllably movable in at least one direction of translation substantially within the focal plane of said lens assembly,   a rotatable optical element which, with said lens system and said imager, forms an optical train which images external objects onto said imager, said rotatable optical element being positioned to steer the field of view of said optical train;     imaging the desired area, while maneuvering the air vehicle freely; and   moving said imager during said imaging step, to compensate at least partially for motions of the air vehicle,   wherein said imager is moved within said focal plane to compensate for yaw and crab of the air vehicle.   
     
     
       21. A method for performing aerial reconnaissance, comprising the steps of: flying an air vehicle along a track which is within view of a desired area to be imaged, wherein said air vehicle includes: a lens system mounted substantially fixedly;   an electro-optic imager mounted in the focal plane of said lens system, wherein said imager is controllably movable in at least one direction of translation substantially within the focal plane of said lens assembly,   a rotatable optical element which, with said lens system and said imager, forms an optical train which images external objects onto said imager, said rotatable optical element being positioned to steer the field of view of said optical train;     imaging the desired area, While maneuvering the air vehicle freely; and   moving said imager during said imaging step, to compensate at least partially for motions of the air vehicle,   wherein said imager is also movable normal to said focal plane to achieve a desired range focus.   
     
     
       22. A method for performing aerial reconnaissance, comprising the steps of: flying an air vehicle along a track which is within view of a desired area to be imaged;   wherein said air vehicle includes: a substantially fixed lens system mounted to image ground-level objects onto a substantially linear electro-optic imager movably mounted in the focal plane of said lens system,   wherein said imager is a substantially linear imager, and is controllably movable to move substantially within the focal plane of said lens assembly with at least two degrees of freedom,   and wherein said imager and said lens assembly are aligned in an optical train to image a desired portion of a ground surface external to the air vehicle onto said imager, and wherein said optical train includes at least one rotatable element such that the ground region imager onto said imager can be changed by rotating said rotatable element, apart from any changes in the attitude or position of said air vehicle;     imaging the desired area, while maneuvering the air vehicle freely; and   moving both said imager and said rotatable element during said imaging step, to compensate for motions of the air vehicle about both pitch and roll axes thereof,   wherein said rotatable element is mounted to rotate about an axis which is substantially parallel to the roll axis of the air vehicle, and wherein said imager is translated in accordance with pitch axis motions of the air vehicle.   
     
     
       23. A method for performing aerial reconnaissance, comprising the steps of: flying an air vehicle along a track which is within view of a desired area to be imaged;   wherein said air vehicle includes: a substantially fixed lens system mounted to image ground-level objects onto a substantially linear electro-optic imager movably mounted in the focal plane of said lens system,   wherein said imager is a substantially linear imager, and is controllably movable to move substantially within the focal plane of said lens assembly with at least two degrees of freedom,   and wherein said imager and said lens assembly are aligned in an optical train to image a desired portion of a ground surface external to the air vehicle onto said imager, and wherein said optical train includes at least one rotatable element such that the ground region imager onto said imager can be changed by rotating said rotatable element, apart from any changes in the attitude or position of said air vehicle;     imaging the desired area, while maneuvering the air vehicle freely; and   moving both said imager and said rotatable element during said imaging step, to compensate for motions of the air vehicle about both pitch and roll axes thereof,   wherein motion of said imager within said focal plane is controlled to compensate for motions of the air vehicle about the yaw axis thereof.   
     
     
       24. A method for performing aerial reconnaissance, comprising the steps of: flying an air vehicle along a track which is within view of a desired area to be imaged;   wherein said air vehicle includes: substantially fixed lens system mounted to image ground-level objects onto a substantially linear electro-optic imager movably mounted in the focal plane of said lens system,   wherein said imager is a substantially linear imager, and is controllably movable to move substantially within the focal plane of said lens assembly with at least two degrees of freedom,   and wherein said imager and said lens assembly are aligned in an optical train to image a desired portion of a ground surface external to the air vehicle onto said imager, and wherein said optical train includes at least one rotatable element such that the ground region imager onto said imager can be changed by rotating said rotatable element, apart from any changes in the attitude or position of said air vehicle;     imaging the desired area, while maneuvering the air vehicle freely; and   moving both said imager and said rotatable element during said imaging step, to compensate for motions of the air vehicle about both pitch and roll axes thereof,   wherein said imager is movable within said focal plane with two degrees of freedom, including rotation and one direction of translation.   
     
     
       25. A method for performing aerial reconnaissance, comprising the steps of: flying an air vehicle along a track which is within view of a desired area to be imaged;   wherein said air vehicle includes: a substantially fixed lens system mounted to image ground-level objects onto a substantially linear electro-optic imager movably mounted in the focal plane of said lens system,   wherein said imager is a substantially linear imager, and is controllably movable to move substantially within the focal plane of said lens assembly with at least two degrees of freedom,   and wherein said imager and said lens assembly are aligned in an optical train to image a desired portion of a ground surface external to the air vehicle onto said imager, and wherein said optical train includes at least one rotatable element such that the ground region imager onto said imager can be changed by rotating said rotatable element, apart from any changes in the attitude or position of said air vehicle;     imaging the desired area, while maneuvering the air vehicle freely; and   moving both said imager and said rotatable element during said imaging step, to compensate for motions of the air vehicle about both pitch and roll axes thereof,   wherein said imager is also movable normal to said focal plane to achieve a desired range focus.